This invention relates to the field of network management, and in particular a method of determining resource availability in a digital communications network.
The calculation of availability for resources in a network is often based on a simple binary state (i.e. available or unavailable). Subsequently, calculations of availability for a set of inter-related resources are limited to an overall binary state as well. In the case of certain combinations of resources, the unavailability of one resource does not result in a simple state for the aggregate of resources. For example, one branch of a set of parallel resources being unavailable does not mean that the whole set is either available or unavailable.
An object of the invention is to alleviate this problem.
According to the present invention there is provided a method of determining the availability of a network resource in a digital communications network, comprising the steps of identifying atomic resources that are not composed of other resources, assigning a degradation factor to each atomic resource, and subsequently deriving a degradation factor for a composite resource from the degradation factors of the atomic resources in accordance with a predetermined relationship.
The calculation of availability using the concept of degradation requires the assignment of a degradation factor to each atomic resource. Atomic resources are ones that are not composed of any other resources. Atomic resources are combined into composite resources that also have a degradation factor. The degradation factor for the composite resource is derived from some formula applied to all the component (atomic) resources. The degradation factor itself is a preferably real value between zero (0) and one (1) inclusive. A zero value indicates full degradation while 1 indicates full availability.
Atomic resources can be combined using certain basic relationships. These are outlined below:
Serial Relationships
The xe2x80x9cchildxe2x80x9d resources contained within a serial composite resource must always be specified in a specific order.
The degradation factor of the serial resource is always equivalent to the lowest degradation factor from its child resources. This can be represented by the following:
xe2x80x83degradation factor=min (select all degradation factors from child resources)
Parallel Relationships
The xe2x80x9cchildxe2x80x9d resources within a parallel composite resource are not specified in any specific order. Each xe2x80x9cchildxe2x80x9d resources that is part of the composite can be assigned a specific weight. This weight is representative of the importance of this resource within the relationship.
The degradation factor is determined by applying the following formula. This formula (very similar to the availability formula) would be:       degradation    ⁢          xe2x80x83        ⁢    factor    =                    ∑        i            ⁢              (                  child          ⁢                      xe2x80x83                    ⁢          degradation          ⁢                      xe2x80x83                    ⁢          factor          *          child          ⁢                      xe2x80x83                    ⁢          weight                )                            ∑        i            ⁢              child        ⁢                  xe2x80x83                ⁢        weight            
where i represents all child resources.
Redundant Relationships
A redundant relationship can be used to group two resources in a master/standby type of relationship. When an outage would occur on the master, the relationship would then take on the characteristics of the standby resource. In this case, the degradation factor of the parent resource could reflect the loss in throughput caused by the switch to the standby.
Hybrid Relationships
A hybrid relationship can be used to group disparate resources into a composite resource. Various hybrid types could be defined such as atomic-serial and atomic-parallel, serial-parallel, serial-serial, etc, etc . . .
For example, an atomic resource representing an ATM card can be grouped with a parallel composite resource that represents all of the ATM ports on that card. Certain performance attributes could be derived from the card object while other performance attributes could be derived from the collection of ports.
In the case of a hybrid relationship, the degradation factor would be equivalent to the degradation factor of a predetermined component. Using the example between an ATM card and its ports, the degradation factor of the parent resource could be configured to be equivalent to either that of the card or the set of ports.
Thus, instead of expressing the availability of a telecom network component as a function of its state, which does not work very well in cases where a component does not have a meaningful state, the invention permits the wellness of a component to be expressed in terms of a degradation factor. The degradation factor would be an attribute that would be expressed as a value between 0 and 1. A resource that is completely well would have its degradation factor set to 1. A resource that is completely down would have its degradation factor set to 0. Once this is done its availability can be calculated using its historical degradation factor values. The following calculation would be applied:       Availability    ⁢          xe2x80x83        ⁢          (              period        ⁢                  xe2x80x83                ⁢        p            )        =                    ∑        p            ⁢              (                  degradation          ⁢                      xe2x80x83                    ⁢          factor          *          duration                )                    period      ⁢              xe2x80x83            ⁢      p      
The invention permits the operator to perform performance management functions on these network components and gives the ability to handle vendor specific extension including node extensions and version extensions.